SLA prototype is a procedure which using photosensitive resin for laser chemical reaction that occurs on photo-polymerization works. When the molecular weight of the resin after the occurrence of a sharp increase in the liquid photo-polymerization at a UV irradiation, a solid state becomes quickly. And the laser beam is controlled by a computer program, based on the structure of the client's 3D drawing were swept surface, wherever liquid that solidified. Can produce very fine detail, and thin-walled structures of complex shaped products (such as hollow parts, irregular surfaces), many CNC machining invisible details can be processed out, but this kind of rapid prototyping service is a limited choice of materials. It must be resin. It's a little bit different with the real engineering material.